Wastewater Treatment of Electroplating

Wastewater Treatment for Metal Plating Factories

In general, wastewater treatment in metal plating factories involves converting and precipitating chemicals, depending on the specific chemicals used in the plating process. Some chemicals need to be treated first before precipitation occurs. The treatment procedures for various substances are as follows:

1. Cyanide

• pH Adjustment: Adjust the pH of the wastewater to 7-8.

• Treatment: Add chlorine or hypochlorite and stir for several hours.

• Monitoring: After treatment, check the cyanide levels. If cyanide remains, add more chlorine or hypochlorite and stir until it is completely removed.

2. Hexavalent Chromium (Cr6+)

• pH Adjustment: Adjust the pH of the wastewater to 8-9.

• Treatment: Add sodium bisulfite and stir until hexavalent chromium is reduced to trivalent chromium (Cr3+) completely.

3. Heavy Metals

• pH Adjustment: Adjust the pH of the wastewater to 7-11, depending on the type of metal.

• Precipitation: Heavy metals will precipitate out of the water when the pH is properly adjusted. Let the precipitate settle at the bottom of the tank before removing the water.

• Organic Matter Decomposition: If the discharged water has excessive organic matter, biological treatment may be necessary to break down the organic material. If the organic matter is high, it may lower the Dissolved Oxygen (DO) in the water, requiring additional oxygen or chemicals to aid in faster decomposition. Once the water is clean enough, it can be discharged.

Each step ensures that the wastewater is treated effectively before disposal, meeting environmental standards.